Ni-SPAN-C Alloy 902

C Carbon
0.06 max
Mn Manganese
0.80 max
Si Silicon
1.00 max
Cr Chromium
4.90 – 5.75
Ti Titanium
2.20 – 2.75
Al Aluminium
0.30 – 0.80
Ni +(Co) Nickel + Cobalt
41.0 – 43.5
Fe Iron
P Phosphorus
0.04 max
S Sulfur
0.04 max

General characteristics of Ni-SPAN-C alloy 902

Alloy 902 is a nickel-iron-chromium alloy that is precipitation hardenable due to aluminum and titanium additions. The titanium also helps to provide a controllable thermo-elastic coefficient, the alloy’s outstanding characteristic.
The alloy may be processed to have a constant modulus of elasticity at temperatures from -50 to 150ÂşF (-45 to 65ÂşC.)


The alloy finds applications in precision apparatus where elastic members are subject to temperature fluctuations. Some applications are resonant vibratory systems such as electro-mechanical filters, tuning forks and vibratory reeds.
Another important application is springs – Bourdon tubes, aneroid capsules, hairsprings for timing devices, diaphragms and springs for weighing instruments.


In view of the major applications of this alloy, heavy forging does not really apply to its processing.

Heat treatment

If annealing of the material is required it should be performed at 1850ÂşF (1010ÂşC) and in an inert or high-vacuum atmosphere to maintain a bright surface.

Aging of cold-rolled strip at temperatures from 1100-1300ÂşF (595-705ÂşC) will result in greatly improved strength, ductility and toughness properties. Cold-rolled material treated at this temperature for five hours gave 0.2% yield strengths of 165/175Kpsi., UTS values of 180/193Kpsi and elongation values of 8/9.5%. Charpy impact values, at 17/18 ft. lbs are the same at -423ÂşF as they are at room temperature.


Thorough cleaning of surfaces is necessary for welding, brazing or soldering of this material. Parts are best joined in the heat-treated condition.

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